Characterization of a bovine mammary gland PP3 cDNA reveals homology with mouse and rat adhesion molecule GlyCAM-1.

ABSTRACT

A full length PP3 (Proteose-Peptone component 3) cDNA of 679 bp was isolated from a bovine mammary gland cDNA library. The cDNA encodes a signal peptide of 18 amino acids followed by the mature PP3 sequence of 135 amino acids. This polypeptide showed homology with mouse and rat GlyCAM-1 (Glycosylation dependent Cell Adhesion Molecule 1) a protein which has been shown to act as a ligand for lymphocytes. The similarity was most profound between the signal peptides and three short regions of the mature polypeptides. Additionally structural conservation was predicted by computer analysis in the shape of a C-terminal amphipathic helix. PP3 was found to be expressed in mammary gland but not in peripheral lymph nodes, Peyer's pathes, lung, spleen, heart, and muscle.